I've got a 351W with a 750CFM Edelbrock performer carb. It's a new engine with aluminum heads, comp cam, roller rockers, etc. It should be putting out about 400hp.


When I first got on the road with it, it had a pretty bad bog to it and it backfired. I checked the timing, changed to the silver step-up springs in the carb, adjusted the choke, and regulated the feul pressure to about 5.5psi.

The backfiring stopped and the bog improved, but when it's cold, it stumbles on acceleration. I really have to feather the pedal to keep from loading it up. After it runs 10 minutes or so, it's not near as bad, but it still has a bog to it, and the exhaust is pretty pungent. It stings my eyes.

I looked at the spark plugs, and they look fine. I'm just confused because the edelbrock troubleshooting sheet describes "stumbling and loading up" as a rich problem, but "bogging" as a lean problem.

what's the deal?

 

I've got some edelbrock tech on my5oh but you have register to see it. I'll post some here..

The "burning eyes" rich (at idle I presume) is fixed by this procedure:

IDLE MIXTURE

The Edelbrock Performer Series carburetor has conventional Idle Mixture Screws (IMS) that provide a leaner A/F when turned clockwise and richer A/F when turned counter clockwise. The idle air flow is controlled by a conventional screw that opens the Primary Throttles. The following procedure should be used to set the idle mixture and speeds.
1. Fully warm engine and ensure choke is fully open.

2. Air cleaner in place.

3. Set desired speed with the air screw.

4. Adjust the IMS on ONE side to get the maximum possible RPM. Do not go rich beyond the maximum speed point.

5. If the above changed the idle speed more than 40 RPM, then readjust the speed.

6. Adjust the side OPPOSITE of that in Step 4 to get maximum RPM.

7. Reset the speed.

8. Carefully trim each IMS to again get the maximum idle RPM.

9. Go leaner just enough to get a 20 RPM drop in speed.

10. Reset the speed to the desired RPM.

11. This is a Lean-Best Idle Set. Setting richer than this will not improve idle quality or performance, but could tend to foul plugs.

This is about part throttle:

CALIBRATING THE PART-THROTTLE

The Metering Rod feature used in the Edelbrock Performer allows easy calibration of the part-throttle without change to the WOT metering.

Cruise Mode: The power output is low, as in a steady cruise light acceleration. Manifold Vacuum is high and the Metering Rods are down in the lean position.

Power Mode: The power output is high, as in a heavy but not wide-open acceleration. Manifold Vacuum is low and the Rods are up in the rich position.
As explained in the "Theory of Operation," the Step-Up function modulates the Rods between the Cruise and Power positions.

The part-throttle calibration is more "individualized" than is the Wide-Open-Throttle (WOT). It is not measured by absolute numbers, but reflects the driver's feel for a particular combination.

Carefully evaluate the driveability with the carburetor at the calibration level determined from the WOT exercise. Drive at a variety of engine speeds and throttle openings looking for any flat spots or lean/surge conditions

 

sounds to me like the timing is slow.what is it set at?initial and full advance?don't know anything about edelbrock carbs and don't want to but i'd up the fuel pressure to 7-7 1/2 lbs.